Since the light emitting diodes (LEDs) are widely applied in various application fields, many different structures and manufacturing methods for making the light emitting diodes have been developed. For example, U.S. Pat. No. 6,462,358 issued to Lin et al., entitled “Light emitting diode and method for manufacturing the same” discloses a light emitting diode with a transparent substrate which is connected to an epitaxial structure by an adhesive layer. The light emitting diode of Lin et al. has better luminous efficiency due to the lower absorption of light, lower forward voltage and better current distribution of the transparent substrate. However, the light emitting diode may impose a local thermal concentration and further limit its performance due to the low thermal conductivity of the transparent substrate. U.S. Pat. No. 6,458,612 issued to Chen et al., entitled “Method of fabricating high efficiency light-emitting diode with a transparent substrate” also discloses a light emitting diode with a transparent substrate.
For another example, U.S. Pat. No. 6,812,067, issued to Chen et al., entitled “Method for integrating compound semiconductor with substrate of high thermal conductivity” discloses a compound semiconductor structure with a nontransparent substrate, which employs a metal of low melting point to form two bonding layers on the substrate and the epitaxial structure respectively, and connects the substrate with the epitaxial structure by connecting two bonding layers. However, the light emitting diode in U.S. Pat. No. 6,812,067 adopts the high conductivity material for the nontransparent substrate restricting the structure of the light diode.
Therefore, there is a need to provide a light emitting diode and a method making the same suitable for various structures of the light emitting diode to improve the thermal conductivity of the light emitting diode.